Active cooling system for CPU and semiconductors also enabling thermal acceleration

ABSTRACT

An active cooling system for the CPU of a computer having computer slots and motherboard, the cooling system including a card arranged to sit in a computer slot coupled to the motherboard and powered directly from mains via the computer slot, the card including a hot air outlet passage from inside the computer to outside the computer; a cooling-CPU unit including a thermoelectric component (TEC) couplable to mains for power supply, a cold side heat sink coupled to the TEC and in thermally conductive contact with a part of the CPU, a hot side heat sink coupled to the TEC, and a fan distanced from the hot side heat sink for pulling heated air from the hot side heat sink.

FIELD OF THE INVENTION

The present invention relates to a device and method for active coolingof a computer microprocessor (CPU) to speed up the processor, and tosolve heat problems.

BACKGROUND OF THE INVENTION

Processor power, and therefore speed, is increasing rapidly. From thebeginning of personal computers and until now, the trend of CPUincreasing temperature is clear.

The first processor models, such as XT, 286, 386 didn't need any thermalsolutions. Their power consumption and therefore temperature was low.When the 486 came out, it needed a small heat sink [aluminum plateattached to the CPU] to decrease and remove the heat. The heat isincreased due to the number of transistors, also called CMOS devices,located on the silicone wafer, and increasing switching speed. Each CPUmodel had several versions of switching speed, and the switching speedand temperature are correlated.

The Pentium CPU needed a heat sink and a fan. Thus, a whole new marketof passive cooling solutions emerged. Pentium II models came out with adifferent structure, with increasing power and heat. This CPU [andothers such as the AMD Athlon CPU model] needed a very large heat sinkand fan, and sometimes two fans or more. The trend of rising heatcontinued.

The heat of a CPU reduces its reliability, and therefore the reliabilityof the entire computer system, and affects the switching speed.Therefore, decreasing the CPU temperature will allow increasing of theswitching speed. These phenomena are known as thermal acceleration.

The above described conventional cooling systems are all passivesystems. This means that they remove heat from the CPU of the computersystem, but do not actively input cold in order to actively cool the CPUand reduce the temperature of the CPU below ambient surroundingtemperature. At present, passive cooling solutions are close to theirlimit. A new solution and approach are needed.

An attempt was made by Marlow Industries, Inc., Dallas, Tex., USA, toprovide active cooling in its Model ST3404 PC chip cooler in May 1996.This simple device included a DT12-4 Thermoelectric cooler with a smallheat sink, mounted adjacent a PC chip, and coupled to the motherboard.It provided heat dissipation up to 10 Watts and power input should notexceed 5 Volts DC, according to the manufacturer's data sheet. Thedisadvantages of this device are that the total power of heatdissipation is very low, in terms of present day CPU requirements, andthat is powered by the limited power of the power supply of thecomputer, so cannot receive sufficient power to dissipate more heat.

In addition, this TEC unit is inefficient, and therefore produces evenmore heat inside the computer enclosure, which heats other heatsensitive components, such as the hard drive, memory, chip set, etc.

Furthermore, when the computer is turned off or in the case of a powercut, a fast changing temperature vs. time often results in thermalshock, which could change characteristics of the CPU, reducereliability. At the time, these were not a serious problems, as thechange in temperature as a result of cooling was not very large, thethickness of the CPU silicon wafer was relatively large, and many fewertransistors were used than are in use at present and/or are expected tobe used in CPU's in the future. Another problem which arises whenswitching the unit off, is that the fast rise in temperature can causewater condensation in the unit's cold side, which can lead to seriousproblems. Yet another problem is that the heat built up on the hot sideof the thermoelectric module must be removed from the PC box. [Whileapplying cooling to the CPU, the hot side of thethermoelectric-component is much hotter because of its low efficiency,around 30 percent]. Because of these disadvantages, and due to thechanges in CPU power requirements, which could not be satisfied by thisunit, this model ceased to be marketed some two years ago, as largerpassive cooling systems were more efficient than this small activecooling system.

Another computer including an internal cooling system has been proposedby KryoTech, Inc., of West Colombia, S.C., USA. This computer utilizes avapor phase cooling method, and includes a compressor and condenser withgas and moving mechanical parts mounted inside the computer. Thiscooling system increases the overall size of the computer by some30-40%. Kryotec markets an accelerated speed computer, not a genericsolution. Also Kryotech requires a special turn-off procedure to avoidthermal shock and condensation. This procedure must be followed by ahuman user, which can lead to mistakes and damage.

The present invention described below is a complete system that solvesall the problems mentioned. In particular, it is a generic device, whichcan be mounted in any PC.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an active coolingsystem for the CPU of a computer having computer slots and amotherboard, the cooling system including a card arranged to sit in acomputer slot coupled to the motherboard, the card including a hot airoutlet passage from inside the computer to outside the computer, acooling-CPU unit including: a thermoelectric component (TEC) couplablevia the card to the mains for power supply; a cold side heat sinkcoupled to the TEC by a aluminum or copper adapter/extender and inthermally conductive contact with a part of the CPU; a hot side heatsink coupled to the TEC; and a fan distanced from the hot side heat sinkfor pulling heated air from said hot side heat sink, and a flexible hosecoupled between the fan and the hot air inlet passage on the card.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further understood and appreciated fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a schematic illustration of an active cooling system for acomputer CPU constructed and operative in accordance with one embodimentof the present invention;

FIG. 2 is a block diagram illustration of the connections between thesubsystems of the system of FIG. 1;

FIG. 3 is a schematic illustration of a PCI or ISA card constructed andoperative in accordance with one embodiment of the invention;

FIG. 4 is a schematic sectional illustration of a CPU and attached TECcooling unit according to one embodiment of the invention;

FIG. 5 is a front view of one embodiment of a metal bracket according tothe present invention;

FIG. 6 is a flow chart of operation of the TEC cooling unit according toone embodiment of the present invention;

FIG. 7 is a graph depicting the active cooling action of the device ofthe present invention as compared with passive cooling systems; and

FIG. 8 illustrates operation of inverters according to one embodiment ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention described herein is an active cooling system for a CPU andsemiconductors enabling thermal acceleration of the CPU, and uses aThermoelectric Cooler (TEC) component, a component based on the Paltiereffect and well-known in tie relevant industry. When electrical DC poweris supplied to the TEC component, one side of the component becomes verycold and the other side very hot (partly because of heat pulled from theCPU itself, and partly due to the low efficiency of the TEC componentwhich generates additional heat). In operation, the component actuallypumps heat from the cold side to the hot side. The Thermoelectriccomponent has a low efficiency, and demands high power for operation,which is the reason TEC's were generally not considered to be useful forcooling CPU's and other heat producing components. There are many modelsof Thermoelectric coolers, each with different characteristics andrequiring a different power input. For an advanced CPU, a high powerthermoelectric component is needed.

Referring now to FIGS. 1 and 2, there are shown respective schematic andblock diagram illustrations of a cooling system for a computer CPUconstructed and operative in accordance with one embodiment of thepresent invention. The cooling system of the present invention consistsof three-parts:

1. A PCI or ISA card 10. One example of a suitable card 10 is shownschematically in detail in FIG. 3. Card 10 includes a low-profile switchmode mains operated power supply 12 with a high frequency ferrite orplanar transformer, microprocessor control unit 14, battery charger 16,rechargeable batteries 18, a fan 20, a main power connector 22 locatedon metal bracket 24, and a connection 26 to a flexible air pipe. Asecond PCB 28 is mounted on card 10 and serves as a connector to the PCextension slot (not shown) on the motherboard. An enclosure temperaturesensor 29 is provided seated on card 10.

Card 10 is preferably internally split into two sections, as by aseparator 19. In this case, half of the card is used for the electronicsand batteries, and the other half is used for air passage between theback of the card (inside of the computer), the fan 20 and the metalbracket 24 leading through a hot air outlet 27 to the environment. Afront view of one embodiment of a bracket 24 is shown in FIG. 5. As canbe seen, bracket 24 includes mains power connector 22 and an LED 39which indicates when the thermoelectric unit is operating. PreferablyLED 39 is a blue LED to indicate Cold. It is possible to utilize aflashing LED to indicate operational parameters.

2. A cooling-CPU unit 30, with a CPU connector to the mother board (notshown). One embodiment of a suitable cooling-CPU unit 30 is illustratedin FIG. 4. Cooling-CPU unit 30 includes a thermoelectric component 31,such as DT12-6 manufactured by Marlow Industries, Inc., or CP1.4-127-06Lmanufactured by Melcor, US. Thermoelectric component 31 is coupled via athermally conductive material or compound to a cold side heat sink 32and a hot side heat sink 34. Cold side heat sink 32, here illustrated asan aluminum or copper adapter/extender, can have any desired shape,depending on the contact area of the CPU and the thermoelectriccomponent 31. The adapter also extends the distance from the hot sideheat sink allowing insertion of thermal insulation material. The coldside heat sink 32 is attached to a target CPU 36 using a thermallyconductive material 38, such as silicon paste. A fan 40 is mounted on anelevated frame 42 distanced somewhat from the hot side heat sink 34. Fan40 pulls ambient air from the computer enclosure into fins of the hotside heat sink 34. The heated air is pulled out by fan 40 into a rubberpipe connected to the card 10. The whole unit is mounted in a box 44.Box 44 is sealed from all directions except for air inlet openingsadjacent the hot side heat sink 34. It will be appreciated that theshape of box 44 can be any shape required, depending upon the shape andmethod of mounting of the CPU on the motherboard, and CPU model andmanufacturer.

It will be appreciated by those skilled in the art that a cascade ofthermoelectric components can be utilized in cases requiring improvedheat pumping action. In this case, a cascade of two or morethermoelectric components can be provided coupled to one another.Needless to say, such a cascade will also require a greater input powerin order to operate.

Preferably, a buzzer 33 is provided close to bracket 24 in order toprovide an audible indication of system status. Similarly, a connector35 may be provided for output to an RS232 or USB for automatic shutdownof the PC in case the temperature of the CPU rises above apre-determined threshold. In this case, a CPU temperature sensor 54 iscoupled to the microprocessor control unit 14 which, in turn, sends ashut down message to the computer via the card microprocessor.

3. A flexible pipe 50 is connected between the card 10 and thethermoelectric unit 30. Flexible pipe 50 can be formed of any suitableflexible material, such as rubber or plastic. Flexible pipe 50 can bebent in any direction required to fit it and the thermoelectric unitinto the computer enclosure. An electrical connector 52 is alsoconnected between the card 10 and the thermoelectric unit 30. Accordingto the illustrated embodiment, connector 52 is a four wire connector,although a different number of wires can be utilized, such as whencoupling to more than one thermoelectric unit and/or sensors or todeliver DC voltage to the CPU to allow change of speed. When a four wireconnector is utilized, two wires can be used to deliver power from thecard, and the other two wires can be used for the output of a CPUtemperature sensor 54. Temperature sensor 54 measures CPU temperatureand delivers data to the processor located on the card. According to oneembodiment of the invention, the temperature sensor 54 is coupled to adigital display on the bracket 24 or inside the cooling-CPU unit 30 toprovide a visual display of the CPU temperature. According to anotherembodiment, an external auxiliary temperature measuring devices can beutilized to display or read the temperature of the CPU via temperaturesensor 54.

The method of operation of the cooling system of the present inventionis as follows. Card 10 is inserted into an available PC slot, occupyingonly one slot, and accepts mains power via the metal bracket 24 andconnector 22. The mains power enters the switch mode power supply 12[low-profile using planar transformer]. The switch mode power supplyinverts the AC power to a low DC power needed for the Thermo electricmodule, while providing fully isolation between mains and DC power.According to a preferred embodiment, the power components of the switchmode power supply extend into the hot air outlet passage. In this way,the power components can also be cooled by air in the outlet passage.

The card senses the existing voltage of the PC, so if the card powercord is not connected and the PC is switched on, alarm 33 will sound awarning to the user that the cooling unit is not connected.

The microprocessor control unit 14 inside card 10 controls the coolingcurve, maintaining the temperature curve in a way to prevent thermalshock when turning on the PC. A graph illustrating typical temperaturecurves is shown in FIG. 7. If the PC while operating is unplugged fromthe mains or no electricity is present due to power failure, thebatteries 18 on the card will provide backup power. In order to savespace and cost, only a few batteries, generally 1 to 6 cells, preferably4, are used, generating low voltage. This low voltage is not enough topower the thermoelectric component. Therefore, this voltage enters a DCto DC step up converter 60, or any other method, that converts the lowbattery voltage to suitable voltage and power for the thermoelectriccomponent upon command from microprocessor control unit 14. This systemwill allow the thermoelectric component to continue to work a fewminutes while the microprocessor control unit 14 of card 10 slowlyreduces battery voltage according to a desired curve and algorithm, asshown in FIG. 7. When the temperature of the cold side of thethermoelectric component is increased according to this curve by commandof microprocessor control unit 14, it will prevent thermal shock andwater condensation. The temperature of the cold side is measured by CPUtemperature sensor 54 located on the cold side of the thermoelectriccomponent. Via a connector, this information is delivered to the cardmicroprocessor 14. The CPU temperature can be controlled accurately byis controlling the switch mode power supply by the card microprocessoraccording to the sensor temperature measured.

When the computer is turned on, the cooling-CPU unit is turned on whenit senses 5 Volts on the card connector 28. The cooling-CPU unit isturned on to maximum power to provide cooling to the CPU. Ambient airfrom the computer enclosure is pulled into the hot side heat sink ofthermoelectric component 31. As CPU 31 generates heat, this heat isimmediately pumped from the CPU via the cold side of the thermoelectriccomponent and into the hot side heat sink. As air passes through the hotside heat sink fins, it absorbs the heat from the heat sink fins. Theheated air is removed from the cooling-CPU unit by fan 40 and pushedinto flexible pipe 50. From flexible pipe 50, the heated air passesthrough the hot air passage in card 10, and is ejected outside thecomputer enclosure via hot air outlet 27 in metal bracket 24. Thisprevents generation of unwanted heat inside the PC enclosure, thatcontains other heat sensitive components [hard drive, chipset, memory,etc]

Also it may be possible to operate the system without removing theheated air from the PC enclosure. In this case, it is preferable toprovide other means of cooling the PC enclosure.

There is shown in FIG. 6 a flow chart of the operation of microprocessorcontrol unit 14. As can be seen, this includes normal operatingprocedure, i.e., when the computer is on, as well as special automatictemperature control procedure when the computer has been turned off. Itwill be appreciated that the cooling system of the present invention isalso operative to raise the temperature of the CPU, when required. Thus,if the computer is operating under very cold conditions, and thetemperature of the CPU falls below a pre-defined threshold, the polarityof the thermoelectric component is reversed, thereby providing heatpumping into the CPU instead of out from the CPU.

A graph indicating the difference in temperature curves between thesystem of the present invention with anti-thermal shock control (solidline), the present invention without anti-shock control (C1, C2, C3), ascompared with a passively cooled CPU (broken lines), is shown in FIG. 7.

It is a particular feature of the present invention that thethermoelectric component is powered by an independent power supply,i.e., mains or batteries, and not by the power supply of the PC. Thispermits the use of a relatively high power cooling element, athermoelectric cooler, in order to reduce the temperature of a CPUsubstantially below the ambient temperature, which is not possible inany conventional cooling system. This reduction in temperature permitsgreatly increased processing speeds known as thermal acceleration of theCPU (CMOS devices).

It is a further particular feature that the microprocessor control unitprovides automatic control of the temperature curve, so as to preventthermal shock and condensation during shut off.

FIG. 8 illustrates the operation of the inverters. Either operation bythe batteries. Or 5 Volt is taken from the computer bus and 5V and 3.5Volts are output. This permits the speed of the CPU to be greatlyincreased. By changing CPU frequency multiplier (such as connecting thisvoltage to AMD Athlon processor edge connector), the voltage supplied atselected points will change CPU speeds.

It will be appreciated that the invention is not limited to what hasbeen described hereinabove merely by way of example. Rather, theinvention is limited solely by the claims which follow.

What is claimed is:
 1. An active cooling system for the CPU of a computer having computer slots and a motherboard, the cooling system comprising: a card arranged to sit in a computer slot coupled to the motherboard and powered directly from mains via said computer slot, the card including a hot air outlet passage from inside the computer to outside the computer; a cooling-CPU unit including: a thermoelectric component (TEC) couplable to mains for power supply; a cold side heat sink coupled to said TEC and in thermally conductive contact with a part of the CPU; a hot side heat sink coupled to said TEC; and a fan distanced from said hot side heat sink for pulling heated air from said hot side heat sink.
 2. The active cooling system of claim 1, further comprising a flexible hose coupled between said fan and said hot air outlet passage.
 3. The active cooling system of claim 1, wherein said card includes a high power power supply, independent of an internal computer power supply.
 4. The active cooling system of claim 3, wherein said card further includes batteries to provide back-up power in case of a power failure, to prevent thermal shock and water condensation.
 5. The active cooling system of claim 1, further comprising a microprocessor in said cooling-CPU unit arranged to control temperature of the CPU by controlling operation of said TEC.
 6. The active cooling system of claim 5, wherein said cooling-CPU unit further includes a temperature sensor for providing an output indication of CPU temperature to said microprocessor.
 7. The active cooling system of any of the preceding claims, further comprising an alarm operative when said card and cooling-CPU unit are not receiving mains power but the computer is switched on.
 8. The active cooling system of claim 2, further comprising a metal bracket for mounting said card in the slot, said bracket including a connector for providing mains power to said card SMPS AC/DC inverter that provides power to the active cooling system.
 9. The active cooling system of claim 8, wherein said mains power is provided to a low-profile switch mode power supply occupying one computer slot.
 10. The active cooling system of claim 9, wherein said low- profile switch mode power supply includes a planar transformer.
 11. The active cooling system of claim 10, wherein power components of said switch mode power supply extend into said hot air outlet passage to provide cooling of said power components.
 12. The active cooling system of any of the preceding claims, further comprising a visual display of CPU temperature.
 13. The active cooling system of any of the preceding claims, further comprising a blue LED for providing an indication of operation of the system.
 14. The active cooling system of any of the preceding claims, further comprising an extender on said cold side heat sink providing larger distance between the CPU and said hot side heat sink.
 15. The active cooling system of any of the preceding claims, wherein the card is built into a custom PC power supply.
 16. The active cooling system of claim 8, wherein said card works with an external DC source instead of an internal SMPS, by replacing the AC connector by a DC connector, and supplying DC voltage from an external power supply (linear or smps). 